Regeneration of aluminum halide-absorbent solid catalyst



Feb. 11, 1969 H. L. MULLER ET AL REGENERATION OF ALUMINUMHALIDE-ABSORBENT SOLID CATALYST Filed NOV. 14, 1966 388mm 32 on jaw R.RN NM NM 1? N 1 L Rm .3 Q m an? MK i 3 F m T i T a L 3 I I s H a 3 A L LA m AIL lK 3 L Q .3. a MW TNL \NI m W vh\ umw um um M'lvN N R mm M 5fikv m x V V 1 y m. H U K m m 3 w @w Pow w 9 N 0 d H V W w R I. 7 0 3 la 3 m an L k mi. N

ua e ATTORNEY United States Patent 5 Claims ABSTRACT OF THE DISCLOSURE Amethod of improving the initial hydrocarbon conversion activity of acatalyst which has been regenerated by treating the regenerated catalystwith hydrogen gas at an elevated temperature and pressure, whichcatalyst consists essentially of the reaction product of aluminumchloride with the surface hydroxyl groups of asurfacehydroXyl-containing adsorbent solid. The method includescontacting the regenerated catalyst with gaseous anhydrous hydrogenchloride at a pressure in the range of about 15 to 500 p.s.i. for a timesufiicient to permit essentially complete association of the hydrogenchloride with the catalyst. The hydrogen chloride contacting must takeplace prior to contacting the regenerated catalyst with the hydrocarbonto be converted.

This is a continuation-in-part application of Ser. No. 379,325, filedJune 30, 1964 and now abandoned.

This invention relates to methods for regenerating solid aluminumhalide-adsorbent solid hydrocarbon conversion catalysts. Moreparticularly, the invention relates to procedures for improving thehydrocarbon conversion activity of a used catalyst consistingessentially of the reaction product aluminum halide and hydroxyl groupsof surfacehydroXyl-containing adsorbent solid.

Used catalyst is defined as one possessing less catalytic activity thanfresh catalyst of this type, which loss in activity has resulted fromuse in a conversion process involving a hydrocarbon feed. The usedcatalyst may be derived from any of the processes involving a hydrocarbon feed which are catalyzed by aluminum halides and, particularly,by solid catalysts of the type herein defined. The used catalyst fromconversions involving saturated hydrocarbons is particularly amenable tothe regeneration process of the invention. A preferred source of usedcatalyst is that from the isomerization of lower molecular weightparafiins and cycloparaflins, namely, parafiinic hydrocarbons containingfrom 4 to 8 carbon atoms, which can be rearranged, and cycloparaflinscontaining from 6 to 9 carbon atoms, which can be rearranged. Someisomerization processes require the presence of a cycloparafiininhibitor, in which case the hydrocarbon feed may contain not only thedefined lower molecular weight paraffins but also cycloparafiinscontaining from 5 to 9 carbon atoms. Used catalyst from isomerization ofnbutane, n-pentane, and n-hexane is a preferred source of catalyst tothe regeneration process.

It is to be understood that the regeneration process of the invention isapplicable to catalysts of the defined type which have lost some degreeof catalytic activity and the regeneration may be only a partialrestoration of this lost activity. The point at which a catalyst isconsidered to be used is not only a matter of ability to catalyze thereaction but also a matter of economics. It may be desirable toregenerate a fairly active catalyst back to essentially fresh catalystactivity rather than permit the catalyst to pass to a much lower levelof activity and regenerate to a less than fresh activity. Also, it is tobe understood some used catalyst may not be able to be returned to fullactivity; the nature of the process, the nature of the halide, thenature of the surface-hydroXyl-containing adsorbent solid, all thesehave a bearing on the ability of the used catalyst to be regenerated.

Used catalyst of this type can be regenerated to possess a substantiallygreater activity than the used catalyst by treatment with hydrogen gasat a temperature from about 100 F. to about 600 F., and a hydrogenpressure of from about 50 p.s.i. to about 2500 p.s.i. for a timesufficient to obtain the desired degree of activity increase. Thehydrogen gas may include a hydrogen halide corresponding to the halidepresent in the used catalyst.

It has now been discovered that the hydrocarbon conversion activity of aregenerated catalyst is greatly improved by treatment with gaseousanhydrous hydrogen chloride (HCl) prior to resuming hydrocarbonconversion over the regenerated catalyst. By our invention, the catalystis treated with gaseous anhydrous HCl at a temperature in the range of Oto 200 F. at an HCl pressure in the range of 15 to 500 p.s.i. for a timeof up to 100 hours, preferably up to about hours. Near optimum treatingconditions are a temperature of 75 to 150 F., a pressure of -200p.s.i.g., and a time of 5 to 25 hours. After the HCl treatment, theexcess HCl can be removed from the catalyst bed by depressuring, byevacuation, by gas purge, or it can be removed by the hydrocarbonprocess stream when the regenerated and treated catalyst is returned toprocess.

According to our invention a suitable method of regenerating a usedhydrocarbon conversion catalyst of the type consisting essentially ofthe reaction product of aluminum chloride with surface hydroxyl groupsof surface-hydroxyl-containing adsorbent solid comprises the steps of:(1) draining hydrocarbon from the catalyst, (2) contacting the catalystwith hydrogen at a pressure in the range of about 50 to 2500 p.s.i. anda temperature in the range of about 100 to 400 F. for a time of about 1to 100 hours, (3) contacting the catalyst with gaseous anhydrous HCl ata temperature in the range of about 0 to 200 F. for at least about 1hour, and returning the catalyst to process to resume hydrocarbonconversion in the presence of said catalyst.

The preferred catalyst for use in our process, broadly considered, is analuminum halide positioned on surfacehydroxyl-containing adsorbent solidand associated with hydrogen halide. It is preferred that the hydrogenhalide correspond to the particular aluminum halide used. Aluminumchloride is the preferred aluminum halide and will be used in thesubsequent discussion for the purpose of illustration. Morespecifically, the preferred catalyst is the reaction product of aluminumchloride with surface hydroxyl groups of sur-face-hydroxyl-containingadsorbent solid associated with hydrogen chloride.

The term "surface-hydroXyl-containing adsorbent solid includes thevarious forms of silica gel and the various alumina materials, naturaland synthetic, which have a substantial portion of the surface existingin the hydroxyl form, as opposed to the dehydrated oxide form. Noadsorbed water, as such, should be present. Aluminas which can betreated to produce the required surface hydroxyl groups are gamma, eta,and chi forms of alumina. The surface-hydroxyl-containing adsorbentsolids are not significantly active for hydrocarbon isomerization, underthe other conditions of the process, nor is the aluminum chloridereaction product along significantly active; yet, the reaction product,when conjoined with HCl produces more hydrocarbon conversion than do thesame amounts 3 of aluminum chloride and HCl alone, orsurface-hydroxylcontaining adsorbent solid either alone or with HCl,under the other conditions of the process.

Aluminum chloride can exist on the surface of alumina in three forms:reacted with surface hydroxyl groups to form OAlCl groups, chemisorbedAlCl monomer, and as physically adsorbed aluminum chloride. In the caseof silica gel, aluminum chloride can exist on the surface in only twoforms: reacted with surface hydroxyl groups to form OAlCl groups, andphysically adsorbed aluminum chloride. The reacted and chemisorbed formsassociate with HCl and thus form an active catalyst species; however,the chemisorbed monomer form is unstable and the aluminum chloride inthis form tends to be desorbed by process and/or regeneration fluids,thus destroying this catalyst species. This species can be maintained orreplaced, however, by replacing the aluminum chloride, e.g. in solutionin the process stream. On the other hand, the reacted form is quitestable and, for example, the -OAlCl groups are not destroyed byatmospheric pressure inert gas purge at temperatures as high as 700 F.,far above the sublimation temperature of aluminum chloride. Thephysically adsorbed form is even more unstable than the chemisorbedmonomer form and is not a practical catalyst component.

The surface-hydroxyl-containing adsorbent solid should have asubstantial amount of surface area. Only those pores in the adsorbentsolid having diameters greater than about 35 Angstrom units (35 A.) areutilized in forming the catalyst, therefore it is the surface area ofthe pores larger than about 35 A. which is important. The surface ofadsorbent solid pores having diameters greater than about 35 A. istermed herein effective surface and the term effective surface area isused herein to mean the total surface area of an adsorbent solid minusthe surface area attributable to surface within pores having diametersless than about 35 A. The surface areas and pore diameters herein arethose which are determined by nitrogen adsorption techniques. It isdesirable that the surfacehydroxyl-containing adsorbent solid have aneffective surface area in the range of about 25-700 square meters pergram (sq. m./gm.), preferably 50-500 sq. m./gm.

The bauxitic materials which are naturally occurring impure aluminahydrates, such as bauxite and laterite, are a suitable source ofsurface-hydroxyl-containing adsorbent solids. The aluminous materialswhich contain substantial amounts, or even large amounts, of oxidesother than aluminum oxide are suitable for use in preparingsurfacehydroxyl-containing adsorbent to be conjoined with aluminumchloride and HCl. The synthetic material known as silica-alumina, whichis used as a hydrocarbon cracking catalyst, is such a suitable aluminousmaterial.

It is preferred to use alumina materials, synthetic ornaturally-occurring, such as bauxite, as the surface-hydroxyl-containingadsorbent solid for preparation of the catalyst. Any adsorbed molecularwater should be removed from the solid piror to contacting it withaluminum halide, lest the effectiveness of some of the aluminum chlorideto form a catalyst be destroyed by reaction or hydration with the water.Adsorbed water can be removed by drying or calcining the solid; however,if calcination is used it should not be carried out under conditions oftemperature and time so severe as to destroy the surface hydroxylgroups.

A convenient method of ascertaining whether adsorbed water is absent andan effective amount of surface hydroxyl groups is present in aparticular adsorbent solid to be used in preparing catalyst is todetermine the weight loss of the defined solid upon heating to about1832 F. This weight loss is termed loss on ignition (LOI). It has beenfound that satisfactory surface-hydroxyl-containing adsorbent solids arethose which contain little or no adsorbed molecular water and which loseabout 2-10 Weight percent, preferably 48 Weight percent in the case ofthe aluminas and 2-6 weight percent in the case of silica gel, of theiroriginal weight upon being heated to 4 about 1832 F. The weight loss inthese ranges is due, almost entirely, to the destruction of surfacehydroxyl groups with the consequent liberation of water.

The surface-hydroxyl-containing adsorbent solid for use in forming thecatalyst is prepared in any manner providing a substantial portion ofthe effective surface in the hydroxyl form so that there are availablehydroxyl groups for reaction with aluminum chloride. It is preferredthat at least about 50 percent of the effective surface be in thehydroxyl form. Optimally, nearly all of the effective surface is in thehydroxyl form with no molecular water present.

A suitable method of producing a surface-hydroxylcontaining adsorbentsolid is to calcine a silica and/or alumina containing material toproduce an adsorbent solid containing at least one of the followingadsorbent solid forms: silica gel, chi alumina, eta alumina, gammaalumina, or mixtures thereof such as silica-alumina. Suitablecalcination conditions of time and temperature, e.g. a temperature inthe range of about 300 to 1100 F. for a time in the range of about 1-24hours, will produce an adsorbent solid having the required surface areaand pore size properties and a LOI less than about 2-4 percent. Water,as liquid or vapor, is then added to the calcined adsorbent solid in theamount of about 1-5 Weight percent or more. The added Water is permittedto react with the surface of the adsorbent solid to produce surfacehydroxyl groups. This hydrated adsorbent solid is then dried undercarefully controlled conditions so that molecular water is removedwithout destroying an appreciable number of the surface hydroxyl groups.Suitable drying conditions are a temperature in the range of about200-300 F. for a time of about l0l00 hours. Of course, if the adsorbentsolid, such as bauxite for example, as received contains 8-10 percent ormore of water, as determined by loss on ignition, the hydration step maybe omitted.

The catalyst is formed by contacting aluminum chloride with the definedsurface-hydroxyl-containing adsorbent solid and causing the aluminumchloride to react with the surface hydroxyl groups on the surface of thedefined adsorbent solid, thus forming OAlCl groups on the surface.During this reaction one mole of HCl is liberated for each mole of AlClreacted. HCl is caused to associate, mole for rnole with the 0A1Clgroups to form the active catalyst. It is postulated that an -O-AlC1site, when associated with HCl, forms a proton and a negatively chargedspecies, (-O-AlCl which constitutes the actual catalyst.

The aluminum chloride content corresponding to maximum catalyst activityis that amount of aluminum chloride required to provide a monolayer ofreacted aluminum chloride molecules, i.e., reacted with hydroxyl groupsto form --O--AlCl groups, over the effective surface area of the definedadsorbent solid. One gram of aluminum chloride will provide a monolayerof aluminum chloride molecules (or OAlCl groups) over about 534 squaremeters of effective surface area.

The preferred method of preparing the catalyst is to form a dry physicalmixture of aluminum chloride and surface-hydroxyl-containing adsorbentsolid and react the mixture at a temperature in the range of about 0500F., preferably about ZOO-350 F. Normally suflicient pressure is utilizedto minimize sublimation of aluminum chloride from the reaction mixtureto reduce aluminum chloride loss. A flow stream of gas may be used asthe heat transfer medium for heating the reaction mixture and coolingthe reaction products. Hydrogen is a preferred gas, however otherrelatively unreactive gases such as nitrogen, helium, methane, ethane,propane, butane, etc. may also be used. The reaction time requireddecreases as the reaction temperature is increased. At the preferredreaction temperature of ZOO-350 F., a time of about 0.1 to 10 hours isnormally sufiicient to complete the reaction; however, longer reactiontime is not detrimental. HCl is then caused to associate With thereaction product of aluminum chloride and surface-hydroxyl-containingadsorbent solid. This association is carried out at a temperature belowabout 180-200 F. since at higher temperature the association does nottake place. In fact, a fully formed catalyst will liberate HCl if heatedto a temperature of 180-200 F., or higher, even under pressure of 500psi. or more. The association with HCl is conveniently carried out bycontacting the reaction product with anhydrous HCl at a pressure ofabout -500 p.s.i.a. and a temperature in the range of about 60-200 F.One mole of HCl associates for each mole of AlCl which has reacted withthe surface-hydroxyl containing adsorbent solid. A time of about 1-100hours is normally sufiicient to complete the HCl association.

The most desirable ratio of aluminum chloride to the defined adsorbentsolid depends upon the surface-hydroxyl contentof the particularadsorbent solid used. For example, with surface-hydroxyl-containingadsorbent solid particles of about -60 mesh size and having an effectivesurface area of about 230 sq. m./gm., the proportions will normally beabout -35 weight percent aluminum chloride and about 65-75 Weightpercent adsorbent solid. Most catalyst forming reaction mixturescomprise 10-50 weight percent aluminum chloride and 50-90 weight percentof the defined adsorbent solid. The catalyst can be prepared in a greatnumber of particle sizes. The final catalyst configuration is determinedby the configuration of the surface-hydroxyl-containing adsorbent solidused. The catalyst is hygroscopic, therefore care should be taken toavoid contacting the catalyst with moisture.

Illustrations An isomerization process uses the above defined solidcatalyst in fixed bed reactors and operates at a temperature in therange of about 50-15 0 F., and sufficient pressure to maintain a liquidphase in the reactors. The fresh feed, which has been pretreated toreduce sulfur, olefin, and aromatic concentrations to acceptable levels,is fed together with a recycle stream, if desired, to a prefractionator.The prefractionator bottoms contains naphthenes in excess of that amountrequired as cracking inhibitor, heavier components from the fresh feed,and a small quantity of high boiling materials from the recycle stream.This bottom stream can be used as catalytic reforming feed or can beblended directly into gasoline. The prefractionator is operated so thatthe overhead product contains sufiicient cycloparafifins to inhibitcracking in the isomerization reactors. The cycloparaffin concentrationsuitable for inhibiting cracking is in the range of about 3-15 molpercent, preferably 7-15 percent when isomerizing hexanes or mixedpentanehexane feeds, and about 5-10 percent when isomerizing pentanefeed. The cycloparaffins themselves will be isomerized in the process tonearequilibrium composition. Thus, for example, methylcyclopentane canbe used as cracking inhibitor and be simultaneously converted topredominantly cyclohexane which is also an effective cracking inhibitor.

The prefractionator overhead is cooled and fed to the upper section of ahydrogen scrubber. The purpose of this hydrogen scrubber is to removehydrocarbons from the recycle regeneration-hydrogen stream describedbelow. The prefractionator overhead is Withdrawn from the bottom of thehydrogen scrubber and is fed to the reaction section, which comprises aplurality of fixed bed reactors. If desired, the process stream enteringany reactor may be first passed through a bed of solid aluminum chloride(AlCl saturator) to replace A1C13 that may be lost through solubility ofthis catalytic component in reactor effluent and to make up smallsublimation losses which may occur during regeneration.

The reactor effluent is stripped of HCl and then fed to the recyclefractionator, which produces the isomerized product overhead and arecycle stream as bottoms. The HCl from the top of the HCl stripper isrecycled to the reaction section.

The fixed-bed reactors are manifolded with valves and piping so thateach reactor may be isolated from the process stream for regeneration.The manifolding, which will be described below, and which is exemplifiedin the figure, is designed so that each reactor may be located in anyposition along the process stream.

Briefly, regeneration comprises isolating a reactor from the processstream, draining the reactor, heating the catalyst, contacting the hotcatalyst with an atmosphere of hydrogen for a time sufficient toincrease the isomerization activity of the catalyst, cooling thecatalyst such as with a flowing stream of hydrogen under pressure,contacting the gaseous HCl under pressure for a time sufficient toessentially completely react or associate the regenerated catalyst withHCl, depressuring the reactor, filling the reactor with process liquidhydrocarbon, and returning the reactor to process.

In order to minimize the quantity of C and heavier hydrocarbons presentduring regeneration, which would tend to crack and deposit coke on thecatalyst during the heating step, a scrubber is provided to scrub theseheavier hydrocarbons from the recycle hydrogen streams with reactorcharge liquid. This hydrogen scrubber must also be operated underconditions to minimize the hydrogen adsorbed in reactor charge becausehydrogen tends to inhibit the isomerization reaction. Both of thesegoals can be accomplished by operating the hydrogen scrubber at lowpressure, below about psi, and low temperature, below about 100 F. Thishydrogen scrubber may employ any suitable gas-liquid contact means suchas Raschig rings, Berl saddles, bubble-cap trays, etc.

Relatively pure HCl is needed during a potrion of the regeneration cyclefor conducting the HCl treatment of the regenerated catalyst. It can beconveniently obtained by using some of the overhead product from the HClstripper. This lowers slightly the HCl concentration in the onon-process reaction liquid; however, after its use, excess HCl isreturned to the on-process liquid by absorption in the reactor feedpassing through the hydrogen scrubber into which the HCl is passedfollowing its use during the regeneration cycle. This temporaryreduction in the HCl concentration in the process stream has little orno effect on the isomerization conversion provided the HCl concentrationis not allowed to decrease below the minimum required to maintain thealuminum chloridealumina-I-ICI catalyst species. Of course, HCl from anoutside source may also be used.

Example I To illustrate the process of our invention the results of anisomerization test of six months duration during which our invention wasemployed will be described. The charge stock for this test had thefollowing composition.

Component: Weight percent Neohexane 0.4 Diisopropyl 7.8 Methylpentanes53.2 n-Hexane 25 .8 Methylcyclopentane 2.5 Cyclohexane 10.3

This feed material had been previously pretreated to contain aromatic,sulfur and olefin concentrations less than about 10 parts per millionparts by weight (p.p.m.), 1 p.p.m. and 50 p.p.m., respectively. Theplant utilized four reactors manifolded by appropriate valves and pipingso that each reactor could occupy any position from first to lastrelative to the process stream. The system was similar to thatillustrated in the accompanying drawing. The plant was operated withthree reactors on stream in series while the catalyst in the fourthreact-or was being regenerated. Fractionation equipment was provided tostrip HCl from the reactor effluent, to split the product to obtain ahigh octane neohexane fraction, and to rerun the reactor feed forremoval of heavy hydrocarbons. Facilities were pro vided for recyclingHCl and unconverted hexanes. An aluminum chloride saturator was providedto replace slight losses of A1Cl from the reactor system. This saturatorwas manifolded with appropriate valves and piping so that it could belocated prior to any reactor relative to the process stream or not usedat all.

The operating conditions employed for this test are shown below:

Space velocity, wo./hr./wc. 0.15 Reactor average temperature, F 100-115Saturator temperature, F 115 Reactor pressure, p.s.i.g 200 HCl, wt.percent based on feed 5-7 Cycloparafiin inhibitor, Wt. percent on feed-13 1 Weight of 011 per hour per weight of catalyst.

The catalyst used was aluminum chloride-alumina prepared as describedabove from eta phase alumina having a loss-on-ignition at 1852 F. ofabout 2 wt. percent. This loss on ignition has been found by experienceto correspond closely to maximum surface hydroxyl coverage for thisalumina. The catalyst as prepared contained about 28 weight percentaluminum chloride.

The steps of the regeneration procedure used were:

for about 10-15 The catalyst was effectively regenerated during the 30-44 hour hydrogen soak. The 10-15 hour hydrogen chloride treat was usedto replace the hydrogen chloride lost from the catalyst during theprevious steps of the regeneration procedure. With this regenerationprocedure the catalyst activity after regeneration averaged 94 percentof the activity subsequent to the previous regeneration.

The presence of hydrogen in the process stream decreases conversion,0.15 mol percent hydrogen resulting in a 1 to 2 weight percent decreasein the neohexane content of the product. Therefore, precautions weretaken to prevent hydrogen from entering the process stream eitherthrough leakage or by way of the hydrogen scrubber.

The test was voluntarily terminated after 4,373 hours of continuousoperation during which time neohexane production averaged 40.5 weightpercent in the reactor efiluent hexanes.

Another test was conducted employing a pentanehexane feed containing 35weight percent pentanes. The product pentane fraction contained 81weight percent isopentane. The conversion of hexanes to neohexane wasnot aflected by the presence of the pentanes in the feed. These datashow that our process can be successfully used for mixed pentane-hexaneisomerization.

Example H The outstanding improvement in catalytic activity of aregenerated catalyst obtained by treatment according to the presentinvention compared with a catalyst without our treatment is shown inthis example.

Two catalysts were prepared and used for isomerization of hexanes as inExample I. Each of these catalysts was removed from hydrocarbonconversion and regenerated under hydrogen pressure of 575 p.s.i.g. forabout 16 hours at a temperature of 300 F., and then cooled to 75 F. Oneof the catalysts was then treated with HCl gas at 75 F. and p.s.i.g. fora time of 64 hours while the other catalyst was given no HCl treatment.Hexane isomerization was then resumed over each of the catalysts underthe same isomerization conditions which were similar to those employedin Example I with the following results:

Days On 011 With H01 Treatment, N o HQI Treatment,

Relative Activity Relative Activity Thus it can be seen that, althoughthe catalyst which was not treated with HCl according to our inventionpossessed hexane isomerization activity, the catalyst which was HCltreated had a much higher activity and reached the high activity thefirst day.

An illustrative embodiment of a process for isomerizing a mixed hexanefeed in which our invention is advantageously employed is shownschematically in the figure. This illustration is a recycleisomerization process for conversion of low octane hexane isomers intodimethyl butane, primarily neohexane (2,2-dimethyl butane), which can beused as a high octane gasoline blending component. The process is alsosuitable for isomerizing pentanes or mixed pentanes and hexanes.Heptanes may also be present in the feed, however, catalyst life isshortened as the concentration of heptanes in the feed is increased.

Turning now to the figure, charge stock from source 10, which has beenpretreated to reduce sulfur, olefin, and aromatic concentrations toaceptable levels, is charged via line 11 to prefractionator 12 alongwith hexane recycle from line 13. A bottom stream containing naphthenesnot required as cracking inhibitor, any heptanes and heavier portionfrom the fresh feed, and a small quantity of hexanes are withdrawn viavalved line 14. This bottom stream can be reformed or blended directlyinto gasoline. The prefractionator overhead, which contains most of thehexane isomers and suflicient naphthenes to inhibit cracking in theisomerization section, is passed via line 15, through cooler 16 whereinthe temperature of the overhead stream is reduced to about 50 F. Thecooled feed stream is then passed via line 17 into the upper portion ofa hydrogen scrubber 18. The feed stream flows downward through thehydrogen scrubber countercurrently to a rising hydrogen stream,scrubbing from the hydrogen stream any hydrocarbons contained thereinwhich boil above butane. This hydrogen stream is used for regenerationas discussed below. The feed stream passes from the hydrogen scrubberthrough line 19, is joined by HCl recycle from line 20, and is passed tothe reaction section.

For the purpose of illustration, a process employing four reactors isshown and flow through the reaction section will be discussed as thoughreactor R-4 is being regenerated, reactor R-l is the next reactor to beregenerated and thus is in the first position, reactor R-2 is thefreshly regenerated reactor and thus is in the second position, and asthough reactor -R-3 was regenerated prior to reactor R-2, following thelast regeneration of reactor R-1, and thus reactor 'R-3 occupies thethird and last position in the series of reactors on process. Thecombined fresh feed-recycle HCl stream is passed into the feed manifold21, thence through line 22 and valve 23 is opened and valves 23a, 23b,23c, and 23d are closed. The process stream passes upwardly through line24 to reactor R-l, leaving through lines 24a and 25 into cooler 26wherein the exothermic heat of reaction is removed. The cooled reactortR-l efiluent then passes into R-l efliluent manifold line 27, thencethrough valve 28 into aluminum chloride drum inlet line 29. The processstream passes through the aluminum chloride drum 30 into the aluminumchloride drum outlet manifold 31, thence through valve 32a into reactorR-2 inlet line 33 and thence into reactor 11-2. The process stream thenflows from reactor R-2 via lines 34 and 35 through cooler 26a intoreactor R-2 outlet manifold line 37, valve 38a and reactor =R-3 inletline 39 into reactor R-3. The process stream is passed from reactor R-3via line 40, and valve 41 into reaction section outlet manifold line 42,thence into HCl stripper 43. HCl is stripped from the reaction sectioneflluent and is recycled via line 20 to reaction section inlet line 21.HCl-free efiluent is then passed via valved line 44 into the recyclefractionator 45 from which dimethylbutane product is removed via line46. The hexane recycle stream removed from the bottom of the recyclefractionator contains diisopropyl, methylpentanes, normal hexane andcycloparafiins as well as a trace of C7-P111S material. This bottomstream is recycled via valved line 13 to prefractionator feed line 11.

Reactor R-4 is isolated from the process stream for regeneration byclosed valves 47b, 38b, 48c, 23c, 32c, 50, 51, 51a, 51b, and 51c.Hydrogen from source 52 is introduced to reactor R-4 via valved line 53,line 54, hydrogen inlet manifold 54a, valve 550 and line 56. Hydrocarbonis drained from reactor R4 through line 57, valve 49b and line 58 intothe hydrogen scrubber 18. The hydrocarbon from reactor R-4 joins thefeed stream in the hydrogen scrubber 18 and enters the reaction sectionvia lines 19 and 21. Alternatively, a surge drum may be provided intowhich reactor R4, or any other reactor, may be drained prior toregeneration, and from which the reactor may be refilled prior to beingreturned to process. The use of such surge drum will prevent upsettingthe operation of the HCl stripper by intermittent variation in load whena reactor is drained or refilled. Scrubbed hydrogen passes from thehydrogen scrubber via lines 59 through steam heater 60 and is recycledby a compressor (not shown) into line 54a and into reactor R-4 via valve550 and line 56. The recycle hydrogen stream is heated by introducingsteam from source 61 through valve 62 and line 63 into the steam heater60. The hot recycle hydrogen stream in turn heats the catalyst inreactor 11-4 to the preferred regeneration temperature of about 250-300F. When the catalyst in reactor R-4 reaches the desired temperature,steam valve 62 is closed and the hydrogen flow is stopped by thestopping the recycle compressor and closing valves 55c and 49b. The hotcatalyst is allowed to stand in the presence of hydrogen under pressurefor a time sufficient to complete regeneration of the catalyst. Ifdesired a small amount of HCl may be present with the hydrogen.Alternatively isobutane from source 68 may be introduced with thehydrogen via valved line 69 and line 54 to aid in removing olefiniccontaminants from the catalyst by alkylating them. We have found it bestnot to include HCl and isobutane simultaneously. The time required forthe regeneration is normally in the range of about 6 to 72 hours. Afterthe catalyst regeneration is complete, valves 55c and 49b are againopened, the recycle compressor started and the catalyst cooled to about100l50 F. by recycling cool hydrogen via lines 59, 54a, 56, 57, and 58.Although not necessary, it is preferred that the recycle hydrogen usedfor cooling the catalyst contain a small amount of HCl to initiate HCltreatment. The HCl can be introduced into the recycle hydrogen streamfrom HCl storage drum 64 via valved line 65 and line 54 into thehydrogen line 54a. After the catalyst in reactor R-4 is cooled to thedesired temperature, usually 75-125 F., the reactor is depressured bystopping the recycle hydrogen compressor, closing valve 55c andreleasing the hydrogen from the reactor via valve 49b and line 58 intothe hydrogen scrubber and then through lines 59, 54a and valve 80 tovent. Valve 66 is then closed and the reactor is pressured to about150-250 p.s.i. with HCl from recycle line 20 via valved line 67. Thecatalyst in reactor R4 is allowed to stand in the presence of HCl underpressure. A time of 5-15 hours, more or less, is normally suflicient tocomplete the HCl treatment.

When the HCl treatment is completed, valved line 67 is closed and thereactor is again depressured via line 57, valve 4% and line 58 intohydrogen scrubber 18 where the HCl is absorbed in reaction section feed.Valve 49b is then closed and the reactor R-4 is then filled with liquidby opening valves 48c and 50.

When the reactor is filled with liquid, valves 48c and 50 are closed andthen R-4 is put on stream and another reactor is removed from processfor regeneration of the catalyst therein.

As has been pointed out above, HCl is released from the catalyst duringthe heating step of the regeneration sequence. If it is desired toprevent the HCl concentration from building up excessively in theprocess stream during the time a reactor is undergoing hydrogentreatment, HCl may be withdrawn from the system via valved line 77 intoHCl storage drum 64. Make-up HCl is added to HCI storage drum '64 viavalved line 78. If contaminants build up excessively in the HCl recyclestream, a portion of this stream can be purged from the system viavalved line 79. Likewise hydrogen can be purged from the system viavalved line 80.

While our invention has been described herein in connection with aparticular process it is to be understood that other processes mayemploy our invention successfully. While our invention has beendescribed herein in connection with regeneration of the catalyst in aparticular reactor and to a process employing a particular number ofreactors, it should be understood that it is equally applicable toregeneration and HCl treatment of any one or more of the catalyst bedsand to a process employing any number of reactors. While our inventionhas been described as applied to a particular process system, variousalternative processing arrangements and operating conditions will beapparent from the above description to those skilled in the art and arewithin the scope of our invention.

Having thus described our invention, we claim:

1. A method of improving the initial hydrocarbon conversion activity ofa hydrocarbon conversion catalyst consisting essentially of the reactionproduct of aluminum chloride with surface hydroxyl groups ofsurface-hydroxylcontaining adsorbent solid which catalyst has beenregenerated by treating said catalyst with hydrogen at elevated pressureand a temperature in the range of about to 400 F. for a time in therange of about 1 to 100 hours, which method comprises contacting saidregenerated catalyst with gaseous anhydrous HCl at an HCl pressure inthe range of 15 to 500 psi. prior to contacting said catalyst withhydrocarbon to be converted for a time sufiicient to associateessentially completely said catalyst with HCl.

2. The method of claim 1 wherein said contacting with HCl is carried outat a temperature below about 200 F.

3. The method of claim 2 wherein said temperature is in the range ofabout 0 to 200 F.

4. A method of regenerating a used hydrocarbon conversion catalyst ofthe type consisting essentially of the reaction product of aluminumchloride with hydroxyl groups of surtace-hydroxyl-containing adsorbentsolid, which method comprises the steps of:

(1) draining hydrocarbon from said catalyst,

(2) contacting said catalyst with hydrogen at a pressure in the range ofabout 50 to 2500 p.s.i. and a temperature in the range of about 100 to400 F. for a time of about 1 to 100 hours,

(3) contacting said catalyst with gaseous HCl at a temperature in therange of about 0 to 200 F. and at an HCl pressure in the range of 15 to500 p.s.i. for at least about 1 hour.

5. The method of claim 4 wherein said surfacehydroxyl-containingadsorbent solid is adsorbent alumina having essentially no adsorbedmolecular water and a loss on ignition at 1832 F. in the range of about2 to 10 per- 1 1 1 2 cent by weight said loss being essentially entirelydue to 3,210,292 10/1965 Evans et a1 252-411 destruction of hydroxylgroups on said alumina. 3,318,820 5/1967 Muller et a1. 252-415References Cited PATRICK P. GARVIN, Primary Examiner.

UNITED STATES PATENTS 5 Us 2,904,519 9/1959 Cornfield et a1. 252-420252-442 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,427,254 February 11, 1969 Herman L. Muller et a1.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

In the drawing Sheet 1, line 2 and in the heading to the printedspecification, line 3, ABSORBENT" each occurrence, should read ADSORBENTColumn 2, line 69, "along" should read alone Column Column 4, line 64,"flow" 3, line 56, "piror" should read prior should read flowing Column6, line 21, "streams" should read stream line 31, "potrion" should readportion line 36,

cancel "on first occurrence. Column 9, line 32, after "such" insert aColumn 10, line 74, molceu1ar" should read molecular Signed and sealedthis 17th day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUY'LER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

